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Hi Greg,
congratulations on another fine composition.
Just a few comments about this latest effort, and your earlier posting. You have captured probably more than you might realize. I've added a few lines to your "Aurora In The Alps" photo to highlight what I am talking about.
You will see a pair of curved lines at the top. These mark out a very weak "SAR Arc," also known as a 'proton' or 'hydrogen' arc. This is a quite rare auroral phenomenon and usally only occurs during strong geo-magnetic storms. In my experience Kp6 is the minimum level required to get one. The SAR arc is often sub-visual except where it meets the horizon.
The second picture attached is from the first time I encountered one, unfortunately without knowing it. This rough stitch of 5 photos was taken at the start of an all night Great Geo-magnetic Storm on March 31st, 2001. I used a 28mm (film) lens with 30 second exposures on 400 ISO Fuji Film. The bright red, curved horns on the left and right were actually the base of the SAR arc. The rest of this homgenous band passed through my zenith, if I had bothered to look! I think I was too mesmerised by the uplifted 'discrete' or 'green' arc. To see the discrete arc lift off the horizon is rare from here. If you have a close look you will see Corvus in the eastern SAR arc while Eridanus and Rigel are in the western end.
The 3rd line that I have added to your image is the top of the red rays coming off the discrete arc at the bottom. What looks connected in your image is actually a few hundred km's apart! In other words the SAR arc is well ahead (north) of the main display and therefore it appears higher.
During the Mar 31st 2001 storm the whole display remained stable but was steadily reducing in size, actually receeding southwards, for nearly three hours, then all hell broke loose! If you ever catch the "Breakup" of a major auroral storm then consider yourself really lucky. The first 'breakup' often occurs around 11p.m. (non-daylight time) locally and can last up to 40 mins. There can be several 'breakups' in a night.
This sunspot cycle may have another peak to it going by this last display so hopefully we will all get a chance to catch aurora australis again (with apologies to those too far north to see them.)
Cheers
Ian
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